ATMOSPHERE AND PHYSIOLOGICAL REQUIREMENTS

Transcription

1 OXYGEN

2 ATMOSPHERE AND PHYSIOLOGICAL REQUIREMENTS Air at sea level contains about 21% of oxygen at a pressure of 14.7 psi Air above sea level contains the same percentage of oxygen but at a reduced pressure; it also contains less mass of oxygen This has a serious effect on the body s ability to function effectively as there is less oxygen available for the body to absorb into the blood stream and the reduced pressure reduces the rate of absorption feet (cabin) altitude is widely regarded as the maximum altitude at which flying ability is not affected by the lack of oxygen; feet is the level above which the use of supplementary oxygen becomes mandatory Above this altitude, supplementary oxygen must be provided for flight crew, cabin crew and passengers to cater for the following: - Rapid decompression - Smoke and fumes (flight deck only)

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4 SOURCES OF OXYGEN SUPPLY Oxygen can be obtained in flight from the following sources: - Gas bottles (always used for Flight Deck supply, may be used for cabin supply) - Chemical generator (used for cabin supply in commercial aircraft) - Liquid oxygen (never used in commercial aviation, still used in some military aircraft) - Catalytically split from atmosphere (too expensive and bulky for large numbers, used in some single seat military fighters) We will be considering only the first 2 of these supply sources

5 JAR OPS 1 REQUIREMENTS - NON-PRESSURISED AIRCRAFT Flight Deck Crew - O 2 for the entire flight time the cabin is above feet Cabin Crew - For cabin altitudes between and feet, O 2 after 30 minutes; O 2 for entire flight above feet 10% of passengers - For cabin altitudes between feet and feet, O 2 after 30 minutes 100% of passengers - O 2 for entire flight time above feet

6 JAR OPS 1 REQUIREMENTS - PRESSURISED AIRCRAFT Flight Deck Crew - For cabin altitudes between and feet, O 2 after 30 minutes - O 2 whenever cabin above feet - Supply not less than: 30 min for aircraft certified to fly up to feet 2 hours for aircraft certified to fly above feet Cabin Crew - For cabin altitudes between and feet, O 2 after 30 minutes - O 2 whenever cabin above feet - Supply not less than 30 minutes Passengers - 10% of passengers for cabin altitudes between and feet, O 2 after 30 minutes - 30% of passengers whenever cabin above feet - 100% of passengers whenever cabin is above feet - Minimum passenger supply is always 10 minutes (allows for descent to feet)

7 JAR OPS 1 - O 2 Requirements Non-pressurised aircraft Flight Deck Cabin Crew O 2 for the entire flight 13,000 Passengers O 2 for the entire flight for 100% of passengers 13,000 O 2 for the entire flight 10,000 13,000 O 2 after 30 minutes 10,000 13,000 O 2 after 30 minutes for 10% of passengers 10,000

8 JAR OPS 1 - O 2 Requirements Pressurised aircraft Flight Deck O 2 for the entire flight 13,000 13,000 O 2 after 30 minutes 10,000 Cabin Crew O 2 for the entire flight 13,000 13,000 O 2 after 30 minutes 10,000 Passengers O 2 for the entire flight 15,000 15,000 For 30% of passengers 14,000 14,000 O 2 after 30 min for 10% of passengers 10,000

9 JAR OPS 1 - O 2 Requirements Supply availability Flight Deck Not less than 30 mins for aircraft certified to fly up to 25,000 Not less than 2 hrs for aircraft certified to fly above 25,000 Cabin Crew Not less than 30 mins Passengers Always 10 mins (this allows for a descent to 15,000 )

10 CONTINUOUS FLOW SYSTEM 1800 PSI 40 psi - cabin psi - flight deck Blow out disc

11 Bottle shut off valve BOTTLE INSTALLATION (SHUT OFF VALVES)

12 FLIGHT CREW DEMAND REGULATOR

13 FLIGHT CREW DEMAND REGULATOR - CONTROL FUNCTIONS ON/OFF lever - Controls supply to regulator Normal/100% lever - Shuts off cabin air to regulator - Supplementary O 2 valve opens - 100% O 2 supplied on demand Emergency lever - Used in the event of smoke/fumes - Biases demand valve towards open - Gives slight (1 or 2 psi) overpressure to ensure any mask leaks are outwards Relief valve - Relieves excess pressure Test button (not shown) - Supplies mask at a pressure higher than emergency to test mask for leaks

14 FLIGHT CREW MASKS (QUICK-DON) Flight crew must have both speech and listen capability when wearing mask Need to wear a headset, as mask only gives speech capability Same system used for smoke/fumes protection Quick-don masks mandatory if aircraft certified above feet Mask must be able to be donned one-handed, over any glasses, within 5 seconds without interfering with primary duties Above feet, one pilot must wear an O 2 mask at all times

15 FLIGHT CREW MASKS (QUICK-DON)

16 PASSENGER OXYGEN SYSTEM Low pressure continuous flow Either gaseous or chemical supply Masks deploy either: - automatically at feet and must be fully deployed (½hung) by feet - Via pilot operated switch Solenoid lock on door (gaseous system is pneumatic; chemical is electrical) No flow in ½-hung position Only get flow when pull down towards face 100% O 2 is supplied to mask; this is then mixed with cabin air through holes in mask and this is what passengers breathe

17 ADVANTAGES AND DISADVANTAGES OF A CHEMICAL GENERATOR Advantages: - Saves weight; no large oxygen bottles - Less complicated; no regulation required - Easier to distribute - Improved reliability and safety - Any fault would only affect a limited number of seats - Simple to maintain - Easy replacement of units - Oxygen released at a steady rate Disadvantages: - Oxygen produced is smelly and unpleasant - Generates a lot of heat - 12 to 15 minutes only (10 as a minimum) - One shot only

18 CHEMICAL GENERATOR Also called a sodium chlorate candle or a chemical candle Sodium Chlorate reacts with iron powder to give off O 2

19 CHEMICAL GENERATOR - INSTALLATION Each installation supplies between 1 and 5 seats Must be enough to supply at least 110% of the passenger seats fitted (for infants, cabin staff moving about cabin when problem occurs, minimum of 2/toilet for mother and baby)

20 PROTECTIVE BREATHING EQUIPMENT 3 Settings: - NORMAL; 2 ltrs/min; 60 minutes - HIGH; 4 ltrs/min; 30 minutes - EMERGENCY; 10 ltrs/min; 12 minutes Available to crew for fire fighting

21 THERAPEUTIC (FIRST AID) OXYGEN Must have sufficient on board for 2% of passengers carried but never less than 2 units

22 SAFETY ASPECTS OF OXYGEN USE Bottle colour - Green in USA and Europe - Black with white neck in the UK Oxygen bottles have different connectors from other gas containers but have been filled with the wrong gas!!! Oxygen must be free from oil, grease, fuel or other contaminants Oxygen is an agent required for combustion and increased concentrations of it can render material more liable to burn